All of them and none of the above...
It's a liquid, permeated by gas bubbles. Also, if you wait long enough it'll dry into a solid....
what hath science wrought..
Foam is an additive to water. When sprayed it gets air into the mix and "suds" up. Fill a pot of water about half way then pour a bunch of liquid dish soap in. Start putting water in with your faucet and watch the bubbles appear. Same idea as foam
I tried to make helium foam using dish soap and water because I'd seen videos of some company making "flying emoticons" by extruding helium-frothed suds through a cutout with smiley faces or what have you and then cutting the resulting foam tower, letting the figures float away.
I had planned to use floating blobs of foam as targets for our planes to hit during an event because i figured it was less likely to catch in props than a balloon as well as being more eco friendly than bits of rubber strewn across the place.
Turns out that commercially available balloon gas is only about 30% Helium, with Nitrogen making up the rest. If you want pure Helium it's not only much more expensive, but also comes in high pressure gas bottles which are illegal to transport without a permit here in Germany.
So that idea didn't fly, literally
Kind of a bummer, but then, there were free balloons with the kit the balloon gas came in, so at least we had something to target with our planes, and only one plane ever had its prop blocked and the guy still made a successfull landing so it's all good..